Answer:
A
B

C

D

Explanation:
Considering the first question
From the question we are told that
The spring constant is 
The potential energy is 
Generally the potential energy stored in spring is mathematically represented as 
=>
=>
=>
Considering the second question
From the question we are told that
The mass of the dart is m = 0.050 kg
Generally from the law of energy conservation

=> 
=> 
Considering the third question
The height at which the dart was fired horizontally is 
Generally from the law of energy conservation

Here KE is kinetic energy of the dart which is mathematical represented as

=> 
=> 
=> 
Considering the fourth question
Generally the total time of flight of the dart is mathematically represented as

=> 
=> 
Generally the horizontal distance from the equilibrium position to the ground is mathematically represented as

=> 
=> 
The dance that was being created was Hip Hop dance!
Answer:
0.5747 or 57.4%
Explanation:
Your question is not complete so i will assume the right question goes thus;
A Carnot engine extracts 529 J of heat from a high-temperature reservoir during each cycle, and rejects 225 J of heat to a low-temperature reservoir during the same cycle. What is the efficiency of the engine?
Efficiency of a Carnot engine is given by [(Th-Tc) / Th]
using the formula above, the resulting equation will give us; (529-225)/529
=0.574669